Effect of exciton-optical phonon interactions on the binding energies of excitons in ionic quantum well structures

We have derived an expression for the effective interaction potential between the constituents of an exciton, namely an electron and a hole in an ionic quantum well structure by taking into account the electron-hole interactions with the confined optical, interface and half-space longitudinal optical phonon modes using a variational method. We follow an approach similar to that used by Haken to derive an effective potential between an electron and a hole in bulk ionic crystals. Using our interaction potential we have calculated the binding energies of excitons in several ionic quantum well structures. We find that the values of the exciton binding energies calculated using this effective interaction potential are always larger than those obtained using a Coulomb potential screened by the static dielectric constant. We compare our results with those of some recent calculations.